Armor proficiency works in groups based on the relative weight of the armor. There are three primary groups (light, medium, and heavy), plus shields, tower shields, and two forms of exotic armor.
Flexible armor is cleverly designed to be much lighter than normal armor, but just as effective when used by someone who knows how. Medium armor is reduced by five pounds and base armor bonus reduced by one. If used by someone proficient, the armor bonus goes back to normal, maximum Dexterity bonus is increased by one, armor check penalty is reduced by one and arcane spell failure chance is reduced by 5%. The armor bonus returns to the lower rate if the wearer is denied Dexterity bonus to armor class. For heavy armor, all numbers are doubled.
Reinforced armor is specially-reinforced to offer increased protection. Medium armor is five pounds heavier, has +1 armor bonus, maximum Dexterity decreased by one, armor check penalty increased by one, and arcane spell failure is increased by 5%. If proficient maximum Dexterity bonus, armor check penalty, and arcane spell failure chances return to normal. For heavy armor, all numbers are doubled.
| Prereqs | Armor Proficiency (Light), Armor Proficiency (Medium) |
| Benefit | See Armor Proficiency (light). |
| Normal | See Armor Proficiency (light). |
| Special | Fighters, paladins, and clerics automatically have Armor Proficiency (heavy) as a bonus feat. They need not select it. |
| Depends | Armor Proficiency (Heavy), Armor Proficiency (Medium) |
| Benefit | When you wear a type of armor with which you are proficient, the armor check penalty for that armor applies only to Balance, Climb, Escape Artist, Hide, Jump, Move Silently, Sleight of Hand, and Tumble checks. |
| Normal | A character who is wearing armor with which she is not proficient applies its armor check penalty to attack rolls and to all skill checks that involve moving, including Ride. |
| Special | All characters except wizards, sorcerers, and monks automatically have Armor Proficiency (light) as a bonus feat. They need not select it. |
| Prereqs | Armor Proficiency (Light) |
| Depends | Armor Proficiency (Heavy) |
| Benefit | See Armor Proficiency (light). |
| Normal | See Armor Proficiency (light). |
| Special | Fighters, barbarians, paladins, clerics, druids, and bards automatically have Armor Proficiency (medium) as a bonus feat. They need not select it. |
You have learned to use flexible armor correctly.
| Prereqs | score.bab 1 |
| Benefit | You can use exotic flexible forms of armor you are proficient with, with no loss of armor bonus and improved maximum Dexterity bonus to armor class and reduced arcane spell failure chance. |
| Normal | When using exotic flexible armor, you use the reduced armor rating and normal maximum Dexterity bonus, armor check penalty, and arcane spell failure chance. |
You have learned to use reinforced armor more easily.
| Prereqs | score.bab 1 |
| Benefit | You can use exotic reinforced forms of armor you are proficient with, with normal maximum Dexterity bonus and armor check penalty. |
| Normal | When using exotic reinforced armor, you use the reduced maximum Dexterity bonus and armor check penalty. The armor bonus and arcane spell failure chance remain the same. |
| Prereqs | Shield Proficiency |
| Benefit | When you perform a shield bash, you may still apply the shield's shield bonus to your AC. |
| Normal | Without this feat, a character who performs a shield bash loses the shield's shield bonus to AC until his or her next turn. |
| Special | A fighter may select Improved Shield Bash as one of his fighter bonus feats. |
| Depends | Improved Shield Bash, Shield Focus, Tower Shield Proficiency |
| Benefit | You can use a shield and take only the standard penalties. |
| Normal | When you are using a shield with which you are not proficient, you take the shield's armor check penalty on attack rolls and on all skill checks that involve moving, including Ride checks. |
| Special | Barbarians, bards, clerics, druids, fighters, paladins, and rangers automatically have Shield Proficiency as a bonus feat. They need not select it. |
| Prereqs | Shield Proficiency |
| Benefit | You can use a tower shield and suffer only the standard penalties. |
| Normal | A character who is using a shield with which he or she is not proficient takes the shield's armor check penalty on attack rolls and on all skill checks that involve moving, including Ride. |
| Special | Fighters automatically have Tower Shield Proficiency as a bonus feat. They need not select it. |